import java.io.*;
import java.util.Scanner;

public class newtest {

    public static void main(String[] args) throws IOException {
        int num;
        System.out.println("请输入");
        Scanner scanner = new Scanner(System.in);
        num = scanner.nextInt();
        int result=sum(num);
        FileWriter f = new FileWriter("e:\\ss.txt");

        f.write(num +"\n\t F(n)="+result );
        f.flush();


    }

    static int sum(int num){

        if (num == 0)
           return  0;
        else if (num == 1)
           return  1;
        else
         return sum(num - 1) + sum(num - 2);

    }

}
